Abstract
Soil erosion has been a common environmental problem in the Loess Plateau in China. This study aims to better understand the losses of soil organic carbon (SOC) induced by water erosion. Laboratory-simulated rainfall experiments were conducted to investigate the characteristics of SOC loss induced by water erosion. The applied treatments included two rainfall intensities (90 and 120 mm h-1), four slope gradients (10°, 15°, 20°, and 25°), and two typical soil types- silty clay loam and silty loam. Results showed that the sediment OC enrichment ratios (ERoc) in all the events were relative stable with values ranged from 0.85 to1.21 and 0.64 to 1.52 and mean values of 0.98 and 1.01 for silty clay loam and silty loam, respectively. Similar to the ERoc, the proportions of different sized particles in sediment showed tiny variations during erosion processes. No significant correlation was observed between ERoc values and the proportions of sediment particles. Slope, rainfall intensity and soil type almost had no impact on ERoc. These results indicate that the transportation of SOC during erosion processes was nonselective. While the mean SOC loss rates for the events of silty clay loam and silty loam were 0.30 and 0.08 g m-2 min-1, respectively. Greater differences in SOC loss rates were found in events among different soil types. Meanwhile, significant correlations between SOC loss and soil loss for all the events were observed. These results indicated that the amount of SOC loss was influenced primarily by soil loss and the SOC content of the original soil. Erosion pattern and original SOC content are two main factors by which different soils can influence SOC loss. It seems that soil type has a greater impact on SOC loss than rainfall characteristics on the Loess Plateau of China. However, more kinds of soils should be further studied due to the special formation processes in the Loess Plateau.
Highlights
Soil erosion has become a globally prevalent problem that threatens the ecological environmental quality as well as the sustainable development of economic and society [1, 2]
Average sediment loss rates for events of silty clay loam varied between 20.59 and 64.18 g m-2 min-1, whereas the values for events of silty loam varied in 4.65–121.37 g m-2 min-1
Sediment loss rate for events of silty loam was lower than that for events of silty clay loam; an opposite scenario occurred during high rainfall intensity
Summary
Soil erosion has become a globally prevalent problem that threatens the ecological environmental quality as well as the sustainable development of economic and society [1, 2]. Conventional studies on soil erosion include assessing the damage to soil and crop yield as well as investigating the off-site effects of soil erosion on water quality, runoff, and sediment loads in rivers; while in recent years, the role of soil erosion in global geochemical cycles has been gaining considerable attention [1, 5]. For this reason, the movement of SOC during erosion processes should be elucidated. These factors mainly affect SOC loss by influencing overland flow and rill and interrill erosion processes [16]
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